Compositions and methods for the removal of phosphates and other contaminants from aqueous solutions

ABSTRACT

Compositions and methods for removing phosphates, nitrates and heavy metals from aqueous solutions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/443,815, filed Feb. 27, 2017; which application is a continuation ofU.S. patent application Ser. No. 15/235,325, filed Aug. 12, 2016,abandoned; which application is a continuation of U.S. patentapplication Ser. No. 14/630,876, filed Feb. 25, 2015; now U.S. Pat. No.9,434,624, issued Sep. 6, 2016; which application is a continuation ofInternational Patent Application No. PCT/US2013/057199, filed Aug. 29,2013; which application claims priority to U.S. Provisional ApplicationNos. 61,780,267, filed Mar. 13, 2013, 61/715,812, filed Oct. 18, 2012,and 61/695,201, filed Aug. 30, 2012, each of which is hereinincorporated by reference in its entirety.

TECHNICAL FIELD OF THE INVENTION

The invention relates generally to compositions and methods for removingphosphates, nitrates and heavy metals from aqueous solutions using oneor more crystalline compositions comprised of multiple calcium silicatecrystalline structures and amorphous structures

BACKGROUND OF THE INVENTION

The increasing accumulation of phosphorus, nitrogen and heavy metalsdischarged into the environment from agricultural, storm water run-off,wastewater treatment discharge and other sources is one of the mostsignificant environmental challenges facing the planet. Phosphorus isalso used in fertilizers, and given that phosphate mines are depletingand may be fully depleted within next 100 years, world food supplieswill certainly be impacted.

Elevated phosphorus levels in surface waters leads to eutrophication,which is detrimental to aquatic life. To control eutrophication, the EPArecommends that total phosphates should not exceed 0.05 mg/L (asphosphorus) in a stream at a point where it enters a lake or reservoir,and total phosphorus should not exceed 0.1 mg/L in streams that do notdischarge directly into lakes or reservoirs. To date, phosphorus removalhas been accomplished with flocculation/precipitation methods that usemetal salts such as ferric chloride, aluminum sulfate (alum) and calciumhydroxide (lime). In many cases, these methods require the use ofpolymers to enhance the precipitation and ultimate solids removal.Various methods have been detailed that utilize naturally occurring andsynthesized forms of xonotlite and/or tobermorite to remove phosphorus.These materials are restricted by pH of the solution, as increasing pHcauses bicarbonate ions to convert to carbonate ions, reducing theefficiency of removal. Another method of phosphorus removal is thechemical formation of struvite (ammonium magnesium phosphatehexahydrate). This process requires the introduction of a magnesiumsource, typically magnesium hydroxide, and is dependent on a highammonia level as the ammonium source.

Nitrates are also of concern as increased levels in surface water andgroundwater lead to undesirable levels in drinking water supplies. Thecurrent drinking water nitrate limit is 10 mg/L as nitrogen. Nitrateremoval has most often been accomplished via microbiologicaldenitrification. This process requires the availability of denitrifyingbacteria in a reduced oxygen environment. The bacteria metabolize thenitrate resulting in reduction to nitrite and ultimately nitrogen gas.

Discharges of metal ions into water sources can render water non-potableas well as having adverse affects on aquatic life. In-stream waterquality standards as well as National Drinking Water Standards formetals are very low. Metal ions have most often been removed from waterand wastewater by flocculation/precipitation as metal hydroxides. Thisis typically accomplished by the addition of an alkali such as calciumhydroxide or sodium hydroxide. Typically a polymer is required toenhance flocculation and aid in solids removal. Metal ion removal isalso accomplished by the use of cation exchange resins. This processtypically requires a relatively clean water source that is free ofsuspended solids and oils and greases.

Accordingly, there is a need for compositions and methods for making thesame that are highly efficient at removing phosphate, nitrate, and metalions from aqueous solutions such as water and wastewater. It isespecially preferable that the foregoing compositions are able toprovide sufficient alkalinity necessary for effective phosphate removalwithout requiring additional pH adjustment. It is even more preferablethat the foregoing compositions can be manipulated in ways to adsorbvarious cations and anions given that the aqueous solutions contemplatedin connection with the present invention have differing contaminantprofiles.

It is also highly preferred that the foregoing compositions are safe foruse in removing contaminants from potable water sources and in foodprocessing applications. It is also preferred that the foregoingcompositions can recover phosphate and nitrate in a form that can beused as a fertilizer.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to compositions and methods for removingphosphates, nitrates, and heavy metals from aqueous solutions using oneor more compositions comprised of multiple calcium silicate crystallinestructures and amorphous structures. Compositions in accordance with thepresent invention remove phosphates and nitrates from surface waters,and in some cases can yield a high quality, slow-release fertilizer(5-35-0).

It is an object of the present invention to provide compositions andmethods for highly efficient removal of phosphate, nitrate, and metalions from aqueous solutions such as water and wastewater. It is also anobject of the present invention to provide compositions that are able toprovide sufficient alkalinity necessary for effective phosphate removalwithout requiring additional pH adjustment. It is also an object of thepresent invention to provide compositions that can be manipulated inways to adsorb various cations and anions. It is also an object of thepresent invention to provide compositions that are safe for use inremoving contaminants from potable water sources and in food processingapplications. It is also an object of the present invention to providecompositions that can recover phosphate and nitrate in a form that canbe used as a fertilizer.

Aqueous solutions contemplated for applications of the invention includeagricultural run-off, retention ponds, animal farm run-off, animal parkrun-off, streams, lakes, canals, reservoirs, residential and commercialstorm-water run-off, wastewater treatment plant discharge, foodprocessing discharge, industrial wastewater discharge, residentialwastewater discharge, meat processing residuals, toilet water, andaquarium water.

Compositions in accordance with the present invention may be utilized ina variety of applications. In one embodiment, a composition is contactedwith an aqueous solution containing phosphates, nitrates, heavy metalsand/or other contaminants in a reaction chamber that is designed tospeed the rate of contact using centrifugal force. In a relatedembodiment, the reactor uses a Taylor vortex system operated underlaminar flow conditions.

In another embodiment a composition is contacted with an aqueoussolution containing phosphates, nitrates, heavy metals and/or othercontaminants by way of a dry feed or slurry mix into the final DAF orprocess stream (e.g., wastewater final treatment (municipal or foodprocessors)). In another embodiment, a composition is contacted with anaqueous solution containing phosphates, nitrates, heavy metals and/orother contaminants by way of an AdEdge™ Filtration System (e.g., highconcentration nutrient removal).

In another embodiment, a composition is contacted with an aqueoussolution containing phosphates, nitrates, heavy metals and/or othercontaminants by way of a portion injector (e.g., for use with a urinalor toilet).

In another embodiment, a composition is contacted with an aqueoussolution containing phosphates, nitrates, heavy metals and/or othercontaminants by way of dry or slurry broadcast or crop dusting (e.g., onthe ground or on a surface water body).

In another embodiment, a composition is contacted with an aqueoussolution containing phosphates, nitrates, heavy metals and/or othercontaminants by way of a buried barrier (e.g., a sheet comprising thecomposition buried below the surface of an animal farm or park or usedto capture aquarium filtrate for removing phosphates).

BRIEF SUMMARY OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a phosphorus adsorption isotherm for a first composition(Composition A) in accordance with the invention.

FIG. 2 is a phosphorus adsorption isotherm for a second composition(Composition B) in accordance with the invention.

FIG. 3 is a phosphorus adsorption isotherm comparing Composition B toother phosphorus removal methods.

FIG. 4 is a nitrate adsorption isotherm for Composition B.

FIG. 5 demonstrates the affinity of Composition B for a variety of heavymetals.

FIG. 6 demonstrates the efficiency of Composition B on the removal ofarsenic from water as compared to other currently available media.

FIG. 7 is a graph showing phosphorus removal from surface water samplesobtained from a phosphorus mining operation utilizing Composition B.

FIG. 8 is an EDS spectrum of Composition B.

FIG. 9 shows the XRD spectrum of Composition B.

FIG. 10 shows how the spatial orientation of the atoms within thecalcium silicate molecules may be altered resulting in changes in bondlengths and or bond angles.

FIG. 11 shows the effect of the addition of calcium ions to CompositionB's efficiency in removing phosphorus from solution.

FIG. 12 is a phosphorus adsorption isotherm for a third composition(Composition C) in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to methods of producing a compositioncapable of removing phosphates, nitrates and heavy metals from asolution comprising: (a) forming a slurry comprising calcium oxide,silicon dioxide, an alkali, and a solvent; and (b) producing thecomposition capable of removing phosphates, nitrates and heavy metalsfrom a solution by subjecting the slurry to a hydrothermal process undersufficient pressure and for sufficient time to form the composition. Theforegoing composition may be interchangeably referred to as a“hydrothermal residue”. In some embodiments, the methods comprise anadditional step (c) of heating the composition/hydrothermal residue at atemperature and for a time sufficient to increase theefficiency/effectiveness of the resultant composition at removingphosphates, nitrates and/or heavy metals from a solution.

In certain embodiments, the alkali is selected from the group consistingof ammonium hydroxide, calcium hydroxide, magnesium hydroxide, potassiumhydroxide and sodium hydroxide. In some embodiments, the alkali may bein the form of a liquid alkali that comprises an alkali solute and thesolvent. In some embodiments, the solvent is water or comprises water.In other embodiments the solvent is a liquid into which the calciumoxide, silicon dioxide and alkali are at least partially miscible, e.g.,other polar protic solvents such as acetic acid, t-butanol, ethanol,formic acid, isopropanol, methanol and nitromethane. Mixtures of polarprotic solvents are also acceptable.

In some embodiments, the molar ratios of the calcium oxide, silicondioxide and liquid alkali is 2.7:2.5:1 respectively. In relatedembodiments, the foregoing molar ratios may be varied independently by±1%, ±2%, ±3%, ±4%, ±5%, ±6%, ±7%, ±8%, ±9% or ±10%. For example, themolar ratio of the calcium oxide:the silicon dioxide:the alkali in theslurry in one embodiment ranges from 2.43-2.97:1.12-1.38:0.9-1.1.

In particular embodiments, the slurry may additionally comprise a highermolar ratio of calcium oxide in order to achieve higher alkalinity. Insome embodiments, the molar ratio of calcium oxide, silicon dioxide, andalkali is 2.7:1.25:1. In related embodiments the foregoing molar ratiomay be varied independently by as much as by ±1%, ±2%, ±3%, ±4%, ±5%,±6%, ±7%, ±8%, ±9% or ±10%.

The present invention also relates to methods of producing a compositioncapable of removing phosphates, nitrates and heavy metals from asolution comprising (a) forming a slurry comprising calcium oxide,silicon dioxide, an alkali, a solvent and a metal halide salt; and (b)subjecting the slurry to a hydrothermal process under sufficientpressure and for sufficient time to form the composition. The foregoingcomposition may be interchangeably referred to as a “hydrothermalresidue”. In some embodiments, the methods comprise an additional step(c) of heating the composition/hydrothermal residue at a temperature andfor a time sufficient to increase the efficiency/effectiveness of theresultant composition at removing phosphates, nitrates and/or heavymetals from a solution.

In related embodiments, the metal halide salt is selected from the groupconsisting of aluminum chloride, ferric chloride, lanthanum chloride,and magnesium chloride. In some embodiments, the molar ratio of thecalcium oxide:the silicon dioxide:the alkali:metal halide salt is54:25:20:5.5. In related embodiments, the foregoing molar ratios may bevaried independently by ±1%, ±2%, ±3%, ±4%, ±5%, ±6%, ±7%, ±8%, ±9% or±10%. For example, the molar ratio of the calcium oxide:the silicondioxide:the alkali:the metal halide salt in one embodiment ranges from48.6-59.4:22.5-27.5:18-22:4.95-6.05.

In some embodiments, the slurry may additionally comprise one or moreamorphous compounds. In other embodiments, the calcium ion concentrationand/or pH of the slurry may be increased by adding or more calcium saltsand/or soluble alkaline earth salts.

In some embodiments, the hydrothermal process is carried out under atleast about 13.5, 14, 14.5, 15, 15.5, 16 or 16.5 psi of pressure. Inrelated embodiments, the slurry is subjected to the hydrothermal processfor at least 1, 2, 3, 4, 5 or as many as 6 hours. The hydrothermalprocess may involve, for example, a sealed or covered reaction vesselheated at 121° C. (±10%) such that the equivalent of the temperaturegenerated by the foregoing range of steam pressures is achieved. Inthese embodiments, the reaction vessel may consist of a heated“jacketed” ball mill and or a sealed pressure pot or covered reactionvessel.

In embodiments involving an additional “activation” step (i.e., step(c)), the composition/hydrothermal residue is heated for at least 27minutes as low as 540° C. to as high as 660° C. In related embodiments,the composition/hydrothermal residue is heated for at least 28, 29, 30,31, 32 or 33 minutes up to 12 hours. The activation step may beaccomplished by using, for example, a muffle furnace, electric kiln, ora gas kiln.

The present invention also relates to compositions produced by theforegoing methods. Compositions in accordance with the present inventionmay also be characterized by methods of chemical analyses known in theart, for example, scanning electron microscopy (SEM) used in conjunctionwith energy dispersive spectrometry (EDS) or x-raycrystallography/diffraction (XRD). In one embodiment, a composition inaccordance with the present invention has the EDS spectrum shown in FIG.8. In another embodiment, a composition in accordance with the presentinvention has the XRD spectrum shown in FIG. 9.

The composition as shown in FIG. 9 comprises two different crystallinestructures of calcium silicate (Ca₂SiO₄). XRD spectrum data forComposition B also indicated that in addition to the two separateCa₂SiO₄ structures, the following crystal structures were also present:Ca(OH)2, NaCl, SiO₂ and CaCO₃. The XRD spectrum data was obtained usingCu-Kα radiation.

Specific crystalline structure may be altered through compositionvariation and/or temperature and/or pressure variations. Spatialorientation of the atoms within the calcium silicate molecules may bealtered resulting in changes in bond lengths and or bond angles as shownin FIG. 10.

After being removed from a heat source, the resultant crystallinecomposition may be applied to a variety of aqueous solutions. Forexample, in one embodiment the crystalline composition may be contactedwith an aqueous solution in a Taylor vortex system operated underlaminar flow conditions when levels of nitrates, heavy metals and/orother contaminants are very low. In a system arranged in this manner,the reactor fluid dynamics are such that the unique vortex effect causesseveral layers of donut shaped levels of water spinning verticallythrough the donut hole and horizontally along the circumference of thereactor. Centrifugal force causes the crystalline composition and anyother solutes to concentrate along the inner face of the reactor,increasing contact exposure and significantly reducing reaction time andimproving adsorption efficiency.

In another embodiment, the crystalline composition can be applied tocontaminated surface water. Water is pumped from a contaminated pond,lake or canal into a smaller tank or other receptacle. Algae and debrisare removed or returned back to the source. The crystalline compositionis then injected into the effluent flowing in a pipe and mixed using amixing means, causing phosphates, nitrates, and heavy metals to beadsorbed onto the crystalline composition, which then are filtered byway of, e.g., a collection screen. Cleaned water is then discharged backinto the source or into another body of water.

In another embodiment, the crystalline composition can be spread overlakes and ponds, for example by way of a barge, to adsorb and bind tonutrients to lower nutrient levels. The crystalline composition can alsobe mixed in soils to adsorb nutrients which will significantly reducerainwater runoff problems. The crystalline composition may also beburied in a layer below the surface as a barrier which will preventnutrients from entering ground water and aquifers. Multiple (i.e.,staged) applications may be necessary to ensure that the pH ismaintained to avoid harming marine and aquatic life.

In another embodiment, the crystalline composition may be used to treatwastewater by adding the composition directly into a mixed liquor orfinal DAF. After adsorption, the crystalline composition is flocculatedout, processed and disposed of or sold as an edible by-product

In another embodiment, the crystalline composition may be used in anaquarium.

In another embodiment, the crystalline composition s may be dispensedinto a toilet coincident with flushing.

In another embodiment, the crystalline composition may be used as aninorganic polymer flocculant. In still other embodiments, thecrystalline composition comprises another inorganic or organic polymer.

EXAMPLES

The invention is now described with reference to the following Examples.These Examples are provided for the purpose of illustration only, andthe invention is not limited to these Examples, but rather encompassesall variations which are evident as a result of the teachings providedherein.

Example 1

100 mL of a 1 M solution of sodium hydroxide was added to a mixturecomprising 15 g of calcium oxide and 15 g of silicon dioxide at roomtemperature. The resultant slurry was hydrothermally reacted in anautoclave for six hours under 15 psi of steam pressure. The remainingsolids were heated in a muffle furnace at 600° C. for thirty minutes.

FIG. 1 shows a phosphorus adsorption isotherm for the resultantcomposition (“Composition A”).

Example 2

200 mL of a 1 M solution of sodium hydroxide was added to a mixturecomprising 30 g of calcium oxide, 15 g of silicon dioxide, and 15 g offerric chloride hexahydrate at room temperature. The resultant slurrywas hydrothermally reacted in an autoclave for one to six hours under 15psi of steam pressure. The remaining solids were heated in a mufflefurnace at 600° C. for thirty minutes.

FIG. 2 shows a phosphorus adsorption isotherm for the resultantcomposition (“Composition B”).

FIG. 3 is a phosphorus adsorption isotherm comparing Composition B toother phosphorus removal methods.

FIG. 4 is a nitrate adsorption isotherm for Composition B.

FIG. 5 demonstrates the affinity of Composition B for a variety of heavymetals.

FIG. 6 demonstrates the efficiency of Composition B on the removal ofarsenic from water as compared to other currently available media.

FIG. 7 is a graph showing phosphorus removal from surface water samplesobtained from a phosphorus mining operation utilizing Composition B.

FIG. 8 is an EDS graph of Composition B.

FIG. 9 shows the XRD spectrum of Composition B.

FIG. 11 shows the effect of the addition of calcium ions to CompositionB's efficiency in removing phosphorus from solution. ♦ shows the effectof the addition of calcium oxide. ▪ shows the effect of the addition ofcalcium hydroxide.

Example 3

200 mL of a 1 M solution of sodium hydroxide was added to a mixturecomprising 30 g of calcium oxide and 15 g of silicon dioxide at roomtemperature. The resultant slurry was hydrothermally reacted in anautoclave for 3 hours under 15 psi of steam pressure. The remainingsolids were heated in a muffle furnace at 600° C. for 12 hours.

FIG. 11 shows a phosphorus adsorption isotherm for the resultantcomposition (“Composition C”).

Example 4

A more in-depth investigation into the properties and uses ofCompositions A, B and C was conducted. Exemplary chemical and physicalproperties are detailed in Table 1.

TABLE 1 Composition A B C pH 1% solution (10 g/L) S. U. 12.21 12.4212.60 Alkalinity 1% solution (10 g/L) 1560 1570 2400 mg/L as CaCO₃ TotalHardness 1% solution (10 g/L) 540 1948 2340 mg/L as CaCO₃ Density g/cc0.34 0.35 0.38

EDS and XRD analysis performed on Composition B indicates that thematerial is composed of both crystalline and amorphous structures (seeFIGS. 8 and 9). The calcium silicate (Ca₂SiO₄) portion of the materialexists as two separate crystal structures. These crystals of calciumsilicate exist as two separate molecular structures. The XRD data ispresented below. Relative intensity is expressed as a percentage, i.e.,peak height in counts per second (cps) as a percentage of the mostintense peak height. The interplanar spacing (d) and full width halfmaximum (FWHM) are presented as well.

TABLE 2 Peak height Relative Bragg angle 2Θ d (Å) (cps) FWHM (deg)intensity 18.1063 4.89532 208.315 0.3151 28.67409 19.8817 4.4619933.0368 0.2928 4.547442 20.8849 4.24989 73.0344 0.2043 10.05302 23.16363.8367 33.4842 0.4701 4.609025 26.6747 3.33912 464.332 0.1996 63.9142627.4448 3.24714 64.8835 0.204 8.931069 28.7186 3.10595 70.1845 0.31039.66074 29.3996 3.03554 336.784 0.2447 46.35756 31.6566 2.82407 726.4920.1889 100 34.2154 2.6185 267.297 0.3404 36.79283 36.037 2.49021 15.13680.3934 2.083547 39.4625 2.28158 109.214 0.2585 15.03306 41.2618 2.1861559.116 0.2535 8.137185 43.3281 2.08656 16.46 0.5181 2.265682 45.48811.99237 408.821 0.1885 56.2733 47.2604 1.92171 107.694 0.3692 14.8238447.4848 1.91314 85.011 0.3536 11.70157 48.6166 1.87122 39.2806 0.37045.406887 50.137 1.81798 65.8726 0.1421 9.067216 50.8006 1.79578 97.74270.3137 13.45406 54.3658 1.68613 49.5907 0.7577 6.826049 56.523 1.62679118.673 0.2074 16.33507 59.9928 1.54073 43.6149 0.1637 6.003494 62.74631.47958 7.63492 0.9419 1.05093 64.2216 1.4491 20.5574 0.5663 2.8296866.2656 1.40927 47.7325 0.2037 6.570272 68.2524 1.37301 34.818 0.3484.79262 75.3313 1.26058 95.0097 0.2118 13.07787 81.4414 1.18074 12.45640.545 1.714596 84.0006 1.15116 67.5945 0.2521 9.304232 84.7205 1.1432125.5075 0.3976 3.51105 107.4102 0.95571 6.85162 0.8705 0.94311 110.0360.94013 30.6148 0.2791 4.214059

Both Composition A and Composition B were evaluated for their abilityand efficiency in adsorbing ortho-phosphate ion (PO₄ ⁻²). Adsorptionisotherms were prepared with data obtained from laboratory experiments(see FIGS. 1 and 2). Both materials exhibited excellent phosphateremoval efficiency with adsorption ratios around 160-170 mg/g (i.e., mgP per g of Composition A and B). Phosphate adsorption comparisonsshowing Composition B versus various other typical adsorbents aredetailed in FIG. 3. Kinetic rates for the phosphate adsorption reactionare very fast—in the order of minutes for most situations. Thephosphorus removal achieved on the phosphate mining operation surfacewater was achieved after one hour (see FIG. 7). This particular sampleshowed adsorption efficiency approaching 280 mg/g.

The optimal pH range for most efficient adsorption is 9.0-12.5 S.U. and,in most applications, this pH range is achieved by addition of thecomposition. The additional calcium provided by the calcium hydroxideCa(OH)₂ offsets the potentially adverse effect of calcium carbonateCaCO₃ formation at higher pH.

It is believed that the presence of ferric chloride hexahydrate(FeCl₃.6H₂O) in the slurry of Composition B provides compositions inaccordance with the present invention good efficiency for nitrate (NO₃⁻) adsorption. Adsorption isotherms were prepared with data obtainedfrom laboratory experiments (see FIG. 4). Adsorption ratios of around 50mg/g (i.e., mg N per g Composition B) were attained. The optimal pH forthe most efficient adsorption of nitrate is around 6.0 S.U. Due to thehigh alkalinity of Composition B, pH adjustment over the reaction periodis required.

Composition B demonstrates the ability to adsorb heavy metal ions.Removal efficiencies of 93-98% were achieved for chromium (Cr), copper(Cu), lead (Pb), manganese (Mn), and cadmium (Cd) (see FIG. 5). Specificremoval efficiencies are set forth in Table 2.

TABLE 3 Concentration After Application of Initial ConcentrationComposition B Metal μg/L μg/L % Removal Cr 4000 74 98.15 Cu 4000 8098.00 Pb 4000 259 93.53 Mn 4000 89 97.78 Cd 4000 114 97.15

Composition B was also evaluated for its ability to adsorb arsenic (As).Composition B was compared against the commonly used media GFO plus andE33. The comparisons were made using standard downflow packed columntests (see FIG. 6). Removal efficiencies are set forth in Table 3. Theoptimal pH range for most efficient adsorption is 9.0-12.5 S.U.

TABLE 4 Concentration After Initial Concentration Treatment Media μg/Lμg/L % Removal E33 2000 373 81.35 GFO+ 2000 14.1 99.30 Composition B2000 13.6 99.32

Example 5

Adsorbed Phosphate and Nitrate Recovery for Fertilizer Use

Crystals that have adsorbed both phosphate and nitrate are easilyremoved from an aqueous solution via filtration or gravity settling.Drying these crystals may be accomplished by either oven drying orsimple air drying. Based on laboratory isotherms the fertilizer value ofsaturated crystals derived from Composition B is 5-35-0, whichrepresents 5% nitrogen (N), 35% phosphorus as P₂O₅, and 0% potassium(K). In some instances, the fertilizer value may increase as thetreatment of surface water from a phosphate mining operationdemonstrates (57% phosphorus as P₂O₅). See, e.g., FIG. 11.

What is claimed is:
 1. A method of producing a composition capable ofremoving phosphates, nitrates and heavy metals from a solution,comprising: (a) forming a slurry comprising calcium oxide, silicondioxide, an alkali and a solvent, wherein the molar ratio of the calciumoxide:the silicon dioxide:the alkali ranges from2.43-2.97:1.12-1.38:0.9-1.1; and (b) producing the composition capableof removing phosphates, nitrates and heavy metals from a solution bysubjecting the slurry to a hydrothermal process for about 1 to about 6hours under about 13.5 to 16.5 psi of pressure.
 2. The method of claim1, further comprising (c) heating the composition capable of removingphosphates, nitrates and heavy metals from a solution at about 540° C.to 660° C. for at least about 27 minutes.
 3. The method of claim 1 or 2,wherein the alkali is selected from the group consisting of ammoniumhydroxide, calcium hydroxide, magnesium hydroxide, potassium hydroxideand sodium hydroxide.
 4. The method of claims 1-3, wherein the alkali issodium hydroxide.
 5. The method of claims 1-4, wherein the solvent isselected from the group consisting of acetic acid, t-butanol, ethanol,formic acid, isopropanol, methanol, nitromethane, water, and a mixturethereof.
 6. The method of claims 1-5, wherein the solvent compriseswater.
 7. The method of claims 2-7, wherein the heating step of claim(c) is performed at about 600° C. for at least 30 minutes.
 8. A methodof producing a composition capable of removing phosphates, nitrates andheavy metals from a solution, comprising: (a) forming a slurrycomprising calcium oxide, silicon dioxide, an alkali, a solvent and ametal halide salt, wherein the molar ratio of the calcium oxide:thesilicon dioxide:the alkali:the metal halide salt ranges from48.6-59.4:22.5-27.5:18-22:4.95-6.05; and (b) producing the compositioncapable of removing phosphates, nitrates and heavy metals from asolution by subjecting the slurry to a hydrothermal process for about 1to about 6 hours under about 13.5 to 16.5 psi of pressure.
 9. The methodof claim 8, further comprising (c) heating the composition capable ofremoving phosphates, nitrates and heavy metals from a solution at about540° C. to 660° C. for at least about 27 minutes.
 10. The method ofclaim 8 or 9, wherein the alkali is selected from the group consistingof ammonium hydroxide, calcium hydroxide, magnesium hydroxide, potassiumhydroxide and sodium hydroxide.
 11. The method of claims 8-10, whereinthe alkali is sodium hydroxide.
 12. The method of claims 8-11, whereinthe solvent is selected from the group consisting of acetic acid,t-butanol, ethanol, formic acid, isopropanol, methanol, nitromethane,water, and a mixture thereof.
 13. The method of claims 8-12, wherein thesolvent comprises water.
 14. The method of claims 8-13, wherein themetal halide salt is selected from the group consisting of aluminumchloride, ferric chloride, lanthanum chloride, and magnesium chloride.15. The method of claims 8-14, wherein the metal halide salt is ferricchloride hexahydrate.
 16. The method of claims 8-15, wherein the heatingstep of claim (c) is performed at 600° C. for at least 30 minutes.
 17. Acomposition produced by the method of claims 1-16.
 18. A compositioncharacterized by the EDS spectrum shown in FIG.
 8. 19. A compositioncharacterized by the XRD spectrum shown in FIG.
 9. 20. A compositioncomprising calcium silicate, calcium hydroxide, sodium chloride, silicondioxide and calcium carbonate crystal structures characterized by anX-ray diffraction pattern expressed in terms of Bragg angle 2Θ,interplanar spacing, and relative intensity values: Bragg angle 2Θ dRelative intensity 18.1063 4.89532 28.67409 19.8817 4.46199 4.54744220.8849 4.24989 10.05302 23.1636 3.8367 4.609025 26.6747 3.3391263.91426 27.4448 3.24714 8.931069 28.7186 3.10595 9.66074 29.39963.03554 46.35756 31.6566 2.82407 100 34.2154 2.6185 36.79283 36.0372.49021 2.083547 39.4625 2.28158 15.03306 41.2618 2.18615 8.13718543.3281 2.08656 2.265682 45.4881 1.99237 56.2733 47.2604 1.9217114.82384 47.4848 1.91314 11.70157 48.6166 1.87122 5.406887 50.1371.81798 9.067216 50.8006 1.79578 13.45406 54.3658 1.68613 6.82604956.523 1.62679 16.33507 59.9928 1.54073 6.003494 62.7463 1.47958 1.0509364.2216 1.4491 2.82968 66.2656 1.40927 6.570272 68.2524 1.37301 4.7926275.3313 1.26058 13.07787 81.4414 1.18074 1.714596 84.0006 1.151169.304232 84.7205 1.14321 3.51105 107.4102 0.95571 0.94311 110.0360.94013 4.214059


21. A method of removing phosphates, nitrates and/or heavy metals from asolution, comprising contacting and reacting the composition of claims17-20 with a solution containing phosphates, nitrates and/or heavymetals.
 22. The method of claim 21, wherein the solution is containedwithin a reaction chamber and the composition is contacted and reactedwith the solution under centrifugal force.
 23. The method of claim 21,wherein the solution is a final DAF or process stream.
 24. The method ofclaim 21, wherein the composition is contacted and reacted with thesolution by way of a portion injector.
 25. The method of claim 21,wherein the composition is contacted and reacted with the solution byslurry broadcast.
 26. The method of claim 21, wherein the composition isformed into a buried barrier.
 27. The method of claim 21, wherein thecomposition is in the form of a flocculant and further comprises apolymer.